#include <stdio.h>
#include <math.h>
int main()
{
	int m,i,k,flag=1;
	do 
	{
		printf("input a integer:");
		scanf("%d",&m);
	}while(m<=2);
	k=(int)sqrt(m);
	for(i=2;i<=k;i++)
		if(m%i==0)
		{
			flag=0;
			break;
		}
	if(flag)
		printf("%d is a prime mumber .\n",m);
	else
		printf("%d is not a prime mumber.\n",m);
	return 0;
	
}